Generally described, computing devices utilize a communication network, or a series of communication networks, to exchange data. Companies and organizations operate computer networks that interconnect a number of computing devices to support operations or provide services to third parties. The computing systems can be located in a single geographic location or located in multiple, distinct geographic locations (e.g., interconnected via private or public communication networks). Specifically, data centers or data processing centers, herein generally referred to as “data centers,” may include a number of interconnected computing systems to provide computing resources to users of the data center. The data centers may be private data centers operated on behalf of an organization or public data centers operated on behalf, or for the benefit of, the general public.
To facilitate increased utilization of data center resources, virtualization technologies may allow a single physical host computing device to host one or more instances of virtual machine instance configurations that appear and operate as independent computing devices to users of a data center. With virtualization, the single physical host computing device can create, maintain, delete, or otherwise manage virtual machine instances in a dynamic manner. In turn, users can request single computing devices or a configuration of networked computing devices, and be provided with varying numbers of virtual machine resources.
The computing resources provided by the host computing devices may include computing capacity, memory and other storage, bandwidth, and the like. In a data center environment with thousands of host computing devices, an instance of a virtual machine may be instantiated on a random host computing device so long as the target host computing device meets specified criteria such as sufficient and available computing device resources (e.g., processing units, memory, and the like). Once an instance of a virtual machine is instantiated on a physical host computing device, a predetermined amount of one or more computing resources may be reserved for use by the virtual machine instance. A computing resource provider or other operator of the data center environment may guarantee availability, to the virtual machine instance, of the reserved amounts of computing resources on the target computing device.